So the lesson is..
Don't keep incriminating emails, delete them. Warrants are common, court orders are less so.
Of course, keep in mind these two are government employees, and employers are effectively required to archive all employee's email. Lesson two: Do not use your employers computer system, not just email but any part of their network, for personal use. You would be amazed at how easy it is to intercept every bit of communication within your company. SSL can be decrypted and the contents captured when you are using your company's computer, even when the little lock is there.